Cardiovascular System.pptx

Physiology of Cardiovascular System, Cardiac Cycle, Action Potential, Heart Sounds and Murmers, CVS Disorders

1. Cardiovascular System By Dr. Faraza Javaid

2. Introduction Cardiovascular system includes heart and blood vessels . Heart pumps blood into the blood vessels. Blood vessels circulate the blood throughout the body. Blood transports nutrients and oxygen to the tissues and removes carbon dioxide and waste products from the tissues. Your heart is about the size of your clenched fist . It beats about 4000 times an hour and about 100,000 times a day . It will beat over 2 billion times in a lifetime . Each heartbeat pumps half a cup of blood.

3. RIGHT SIDE OF THE HEART Right side of the heart has two chambers , right atrium and right ventricle. Right atrium is a thin walled and low pressure chamber. It has got the pacemaker known as sinoatrial node that produces cardiac impulses and atrioventricular node that conducts the impulses to the ventricles . Right atrium receives venous (deoxygenated) blood via two large veins: Superior vena cava that returns venous blood from the head, neck and upper limbs 2. Inferior vena cava that returns venous blood from lower parts of the body Right atrium communicates with right ventricle through tricuspid valve . From the right ventricle, pulmonary artery arises. It carries the blood from right ventricle to lungs . In the lungs, the deoxygenated blood is oxygenated.

4. LEFT SIDE OF THE HEART Left side of the heart has two chambers, left atrium and left ventricle . It receives oxygenated blood from the lungs through pulmonary veins . This is the only exception in the body, where an artery carries venous blood and vein carries the arterial blood. Blood from left atrium enters the left ventricle through mitral valve (bicuspid valve) . Wall of the left ventricle is very thick. Left ventricle pumps the arterial blood to different parts of the body through systemic aorta.

5. Anatomy Review - The Heart Heart wall Endocardium Myocardium Epicardium Splits into another outside layer – the pericardium The space between the two layers is called pericardial cavity or pericardial space and it contains a thin film of fluid.

6. VALVES OF THE HEART Atrioventricular Valves Left atrioventricular valve is otherwise known as mitral valve or bicuspid valve . It is formed by two valvular cusps or flaps. Right atrioventricular valve is known as tricuspid valve and it is formed by three cusps. Atrioventricular valves open only towards ventricles and prevent the backflow of blood into atria.

7. Semilunar Valves Semilunar valves are present at the openings of systemic aorta and pulmonary artery and are known as aortic valve and pulmonary valve respectively. Because of the half moon shape, these two valves are called semilunar valves. Semilunar valves are made up of three flaps. Semilunar valves open only towards the aorta and pulmonary artery and prevent the backflow of blood into the ventricles.

8. The Pericardium Fixates the heart to the thoracic cavity Relatively inflexible tissue Pericardial sac holds 30-50mL of serous fluid between the pericardium and epicardium, prevents friction during contraction

9. ACTIONS OF THE HEART Actions of the heart are classified into four types: 1. Chronotropic action 2. Inotropic action 3. Dromotropic action 4. Bathmotropic action.

10. CHRONOTROPIC ACTION Chronotropic action is the frequency of heartbeat or heart rate. It is of two types: i . Tachycardia or increase in heart rate ii. Bradycardia or decrease in heart rate

11. INOTROPIC ACTION Force of contraction of heart is called inotropic action. It is of two types: i . Positive inotropic action or increase in the force of contraction ii. Negative inotropic action or decrease in the force of contraction.

12. DROMOTROPIC ACTION Dromotropic action is the conduction of impulse through heart. It is of two types: i . Positive dromotropic action or increase in the velocity of conduction ii. Negative dromotropic action or decrease in the velocity of conduction.

13. BATHMOTROPIC ACTION Bathmotropic action is the excitability of cardiac muscle . It is also of two types: i . Positive bathmotropic action or increase in the excitability of cardiac muscle ii. Negative bathmotropic action

14. BLOOD VESSELS ARTERIAL SYSTEM Arterial system comprises the aorta , arteries and arterioles . Aorta has got the maximum diameter of about 25 mm. Diameter of the arteries is gradually decreased and at the end arteries, it is about 4 mm . It further decreases to 30 μ in the arterioles and ends up with 10 μ in the terminal arterioles . Arterioles are continued as capillaries , which are small, thin walled vessels having a diameter of about 5 to 8 μ . Capillaries are functionally very important because, the exchange of materials between the blood and the tissues occurs through these vessels.

15. VENOUS SYSTEM From the capillaries, venous system starts and it includes venules , veins and venae cavae . Diameter of the venules is about 20 μ . At a time, a large quantity of blood is held in venules and hence the venules are called capacitance vessels. Venules are continued as veins, which have the diameter of 5 mm . Veins form superior and inferior venae cavae , which have a diameter of about 30 mm.

16. COMPLICATIONS IN BLOOD VESSELS Atheroseclerosis Thromboembolism

17. Properties of Cardiac Muscle EXCITABILITY RHYTHMICITY CONDUCTIVITY CONTRACTILITY

18. EXCITABILITY Excitability is defined as the ability of a living tissue to give response to a stimulus . In the tissues, initial response to a stimulus is electrical activity in the form of action potential . It is followed by mechanical activity in the form of contraction, secretion, etc. ELECTRICAL POTENTIALS IN CARDIAC MUSCLE Resting Membrane Potential Resting membrane potential in: Single cardiac muscle fiber : – 85 to – 95 mV Sinoatrial (SA) node : – 55 to – 60 mV Purkinje fibers : – 90 to – 100 mV.

19. Action Potential Action potential in cardiac muscle is different from that of other tissues such as skeletal muscle, smooth muscle and nervous tissue. Duration of the action potential in cardiac muscle is 250 to 350 msec (0.25 to 0.35 sec). Phases of action potential Action potential in a single cardiac muscle fiber occurs in four phases: 1. Initial depolarization 2. Initial repolarization 3. A plateau or final depolarization 4. Final repolarization.

20. Normal Physiology of Heart The cardiac muscles are specialized tissues with unique properties like Contractility Automaticity Excitability Myocardium has two types of cells Contracting cells Conducting cells

21. Contracting cells/ Non-Automatic tissues Atria and Ventricle The contracting cells participate in the pumping action of the heart. Some of the cells have the characteristic property of automaticity. Automaticity is the ability of the cell to generate electrical impulses spontaneously.

22. Conducting cells/ Automatic tissues SA node AV node Bundle of His Bundle branches Purkinje fibers Normally SA node act as pace maker of the heart.

23. Initial Depolarization Initial Repolarization Plateau Phase Final Repolarization

24. RHYTHMICITY Rhythmicity is the ability of a tissue to produce its own impulses regularly . It is also called autorhythmicity or self-excitation. Property of rhythmicity is present in all the tissues of heart. Pacemaker is the structure of heart from which the impulses for heartbeat are produced. It is formed by the pacemaker cells called P cells. In mammalian heart, the pacemaker is sinoatrial node (SA node).

25. CONDUCTIVITY Human heart has a specialized conductive system, through which impulses from SA node are transmitted to all other parts of the heart. Components of Conductive System in Human Heart 1. AV node 2. Bundle of His 3. Right and left bundle branches 4. Purkinje fibers

26. CONTRACTILITY Contractility is ability of the tissue to shorten in length (contraction) after receiving a stimulus . Various factors affect the contractile properties of the cardiac muscle. 1. Absolute refractory period 2. Relative refractory period

27. Arrhythmia Arrhythmia refers to irregular heartbeat or disturbance in the rhythm of heart. In arrhythmia, heartbeat may be fast or slow or there may be an extra beat or a missed beat. It occurs in physiological and pathological conditions.

28. Cardiac Cycle Cardiac cycle is defined as the succession of (sequence of) coordinated events taking place in the heart during each beat. Each heartbeat consists of two major periods called systole and diastole.

29. EVENTS OF CARDIAC CYCLE Events of cardiac cycle are classified into two: Atrial events Atrial Systole Atrial Diastole 2. Ventricular events Ventricular Systole Ventricular Diastole

30. Phases of Cardiac Cycle Ventricular Systole Isovolumetric contraction Rapid ejection Slow ejection Ventricular Diastole Isovolumetric relaxation Rapid filling Atrial Systole

31. Cardiac Cycle Phases

32. Cardiac Cycle Phases Atrium contracts, Mitral valve opened, pressure and blood transferer to ventricle. Aortic valve is closed.

33. Cardiac Cycle Phases Atria relaxed. Pressure in ventricle increases. A/V valve closed (S1)

34. Cardiac Cycle Phases Pressure increases and open the semilunar valves. Blood ejected from ventricle into the vessels.

35. Cardiac Cycle Phases Ventricle relaxed. To prevent back flow of blood, semilunar valves get closed (S2)

36. Phases of Cardiac Cycle Ventricular Systole Duration (approximate) Isovolumetric contraction 0.05 sec Rapid ejection 0.10 sec Slow ejection 0.15 sec Ventricular Diastole Isovolumetric relaxation 0.10 sec Rapid filling 0.10 sec Slow filling (Diastasis) 0.20 sec Filling d/t Atrial Systole 0.10 sec

37. HEART SOUNDS Heart sounds are produced by: 1. Flow of blood through cardiac chambers 2. Contraction of cardiac muscle 3. Closure of valves of the heart

38. DIFFERENT HEART SOUNDS Four heart sounds are produced during each cardiac cycle: 1. First heart sound (S1) 2. Second heart sound (S2) 3. Third heart sound (S3) 4. Fourth heart sound (S4)

39. S1: signals the onset of ventricular contraction whish occurs 50-60 msec after the initiation of ventricular systole frequency ranging from 100-120 Hz. Best heard at apex and lower left sternal border Has mitral (M1) and tricuspid (T1) components

40. S2: Sudden deceleration of retrograde blood flow in the aorta and pulmonary artery which sets the cardiohemic system into vibration Best heard at the base Louder and high pitched than S1 (120-150Hz) Has aortic (A2) and pulmonary (P2) components

41. S1 S2 Systole Diastole Systole Lub Dub

42. Low pitched early diastolic sound Best heard at apex with bell Coin c ides with rapid vent r icul a r fil l ing ( Lu b - Dub-Dum) 0.12-0.18 seconds after S2 Usually pathological in elderly

43. S1 S2 Systole Diastole Systole S3

44. Pathological: Left ventricular failure Severe aortic regurgitation

45. Soft and low pitched Pre systolic or atrial gallop Best heard at apex with bell 0.11 seconds prior to S1 Ca u sed by atr i a l kick ventricle into a n o n com p l i ant

46. S1 S2 Systole Diastole Systole S4

47. Always pathological L VH (Hypert e nsion, Ao r t i c stenosi s , Hypertrophic obstructive cardiomyopathy) Coronary artery disease

48. Cardiac Murmur Cardiac murmur is the abnormal or unusual heart sound. It is also called abnormal heart sound or cardiac bruit. Cardiac murmur is heard by stethoscope, along with normal heart sounds. Murmur is produced because of valvular diseases, septal defects and vascular defects

49. CLASSIFICATION OF MURMUR Cardiac murmur is classified into three types: A. Systolic murmur B. Diastolic murmur C. Continuous murmur

50. Acute severe mitral regurgitation Acute severe tricuspid regurgitation A ortic stenosis P ulmonary stenosis

51. Aortic regurgitation Pulmonary regurgitation Mi t ral stenosi s Tricuspid stenosis

52. CONTINUOUS MURMUR Continuous murmur is the murmur that is heard in conditions such as patent ductus arteriosus. It is a harsh blowing sound and is heard best in the pulmonary area. The murmur is heard 1 year after birth.

53. Cardiac Output Cardiac output is the amount of blood pumped from each ventricle. Usually, it refers to left ventricular output through aorta. Cardiac output is the most important factor in cardiovascular system, because rate of blood flow through different parts of the body depends upon cardiac output.

54. Cardiac output is expressed in two forms : 1) S troke volume 2) Heart rate

55. CO = S V x HR cardiac output = stroke volume X heart rat (ml/minute) (ml/beat) (beats/min) Cardiac output varies widely with the level of activity of the body. CO = S V x HR c a r d i a c o u tp u t = s t r o ke v o l u me X h e a r t rate (ml/minute) (ml/beat) (beats/min) Average heart rate = 70 bpm A verage st r ok e vol u me = 7 0−8 ml/beat Average cardiac output = 5000 ml/minute

56. Cardiac Output Calculation For example: If the heart rate is 70 bpm and stroke volume is 70 ml. Using the formula = HR X SV = 70 X 70 = 4900 ml/min or 4.9 liters per minute.

57. FACTORS MAINTAINING CARDIAC OUTPUT Cardiac output is maintained (determined) by four factors: 1. Venous return 2. Force of contraction 3. Heart rate 4. Peripheral resistance

58. Arterial Blood Pressure Arterial blood pressure is defined as the lateral pressure exerted by the column of blood on wall of arteries . when blood flows through the arteries. Generally, the term ‘ blood pressure ’ refers to arterial blood pressure. Arterial blood pressure is expressed in four different terms: Systolic blood pressure - - 120 ± 20 mmHg (ADULTS) Diastolic blood pressure - 80 ± 16 mmHg (ADULTS) Pulse pressure Mean arterial blood pressure.

59. SYSTOLIC BLOOD PRESSURE Systolic blood pressure (systolic pressure) is defined as the maximum pressure exerted in the arteries during systole of heart. Normal systolic pressure: 120 mm Hg (110 mm Hg to 140 mm Hg). DIASTOLIC BLOOD PRESSURE Diastolic blood pressure (diastolic pressure) is defined as the minimum pressure exerted in the arteries during diastole of heart. Normal diastolic pressure: 80 mm Hg (60 mm Hg to 80 mm Hg). PULSE PRESSURE Pulse pressure is the difference between the systolic pressure and diastolic pressure. Normal pulse pressure: 40 mm Hg (120 – 80 = 40). MEAN ARTERIAL BLOOD PRESSURE Mean arterial blood pressure is the average pressure existing in the arteries. It is not the arithmetic mean of systolic and diastolic pressures. It is the diastolic pressure plus one third of pulse pressure.

60. VARIATIONS Blood pressure is altered in physiological and pathological conditions. Age Gender - in females, arterial pressure is 5 mm Hg, less than in males of same age.

61. PHYSIOLOGICAL VARIATIONS Diurnal variation - in early morning, the pressure is slightly low. It gradually increases and reaches the maximum at noon. It becomes low in evening. 4. After meals - Arterial blood pressure is increased for few hours after meals due to increase in cardiac output.

62. 5 . During sleep - Usually, the pressure is reduced up to 15 to 20 mm hg during deep sleep. However, it increases slightly during sleep associated with dreams. 6 . Emotional conditions - During excitement or anxiety, the blood pressure is increased due to release of adrenaline. 7 . After exercise - After moderate exercise, systolic pressure increases by 20 to 30 mm hg above the basal level due to increase in rate and force of contraction and stroke volume.

63. PATHOLOGICAL VARIATIONS Pathological variations of arterial blood pressure are hypertension and hypotension.

64. HYPOTENSION

65. HYPERTENSION

66. Types of Hypertension Hypertension is divided into two types: Primary hypertension or essential hypertension ( in the absence of any underlying disease) 2. Secondary hypertension (CV, Endocrine, Renal disease)

67. MEASUREMENT OF ARTERIAL BLOOD PRESSURE Blood pressure is measured by two methods: A. Direct method B. Indirect method.

68. INDIRECT METHOD Indirect method is used to measure arterial blood pressure in man as well as in animals. Apparatus Apparatus used to measure blood pressure in human beings is called sphygmomanometer. Along with sphygmomanometer, stethoscope is also necessary to measure blood pressure. Principle When an external pressure is applied over the artery, the blood flow through it is obstructed. And the pressure required to cause occlusion of blood flow indicates the pressure inside the vessel.

69. B lood pressure can be measured by three methods. 1. Palpatory method 2. Auscultatory method 3. Oscillatory method.

70. HEMORRHAGE Hemorrhage is defined as the excess loss of blood due to rupture of blood vessels.   Types And Causes Of Hemorrhage   Accidental Hemorrhage Capillary Hemorrhage Internal Hemorrhage Postpartum Hemorrhage

71. Acute Hemorrhage It refers to sudden loss of a large quantity of blood as in the case of accident. This condition is corrected within 4-6 weeks.   Chronic Hemorrhage It refers to loss of blood by internal or external bleeding over a long period of time. It occurs in conditions like peptic ulcer, purpura and hemophilia.   Purpura, A rash of purple spots on the skin caused by internal bleeding from small blood vessels. Hemophilia is a medical condition in which the ability of the blood to clot is severely reduced, causing the sufferer to bleed severely from even a slight injury.

72. Compensatory Effects Compensatory effects of hemorrhage are of two types. A. Immediate compensatory effects B. Delayed compensatory effects

73. On Cardiovascular System 2. On Skin 3. On Tissue Fluid 4. On Kidneys 5. On Renin Secretion 6. On Secretion of Antidiuretic Hormone 7. On Secretion of Catecholamines 8 . On Nervous System IMMEDIATE COMPENSATORY EFFECTS OF HEMORRHAGE

74. DELAYED COMPENSATORY EFFECTS OF HEMORRHAGE If hemorrhage is not severe, some delayed compensatory reactions occur. These reactions help to restore blood volume, blood pressure and blood flow to different regions of the body. Delayed reactions are: 1. Restoration of plasma volume 2. Restoration of plasma proteins 3. Restoration of red blood cell count and hemoglobin content.

75. REGULATION OF ARTERIAL BLOOD PRESSURE Body has four such regulatory mechanisms to maintain the blood pressure within normal limits: A. Nervous mechanism or short term regulatory mechanism B. Renal mechanism or long term regulatory mechanism C. Hormonal mechanism D. Local mechanism

76. NERVOUS MECHANISM FOR REGULATION OF BLOOD PRESSURE – SHORT-TERM REGULATION Nervous regulation is rapid among all the mechanisms involved in the regulation of arterial blood pressure. When the pressure is altered, nervous system brings the pressure back to normal within few minutes. The nervous mechanism regulating the arterial blood pressure operates through the vasomotor system.

77. VASOMOTOR SYSTEM Vasomotor center is bilaterally situated in the reticular formation of medulla oblongata and the lower part of the pons. Vasomotor center consists of three areas: i . Vasoconstrictor area ii. Vasodilator area iii. Sensory area

78. Baroreceptor Mechanism Baroreceptors are the receptors, which give response to change in blood pressure. Baroreceptors are also called pressoreceptors . Baroreceptors are situated in the carotid sinus and wall of the aorta. Chemoreceptor Mechanism Chemoreceptors are the receptors giving response to change in chemical constituents of blood. Peripheral chemoreceptors influence the vasomotor center. Peripheral chemoreceptors are situated in the carotid body and aortic body.

79. Regulation of blood pressure by baroreceptor mechanism

80. REGULATION OF BLOOD PRESSURE – LONG-TERM REGULATION Kidneys play an important role in the long term. Regulation of arterial blood pressure. When blood pressure alters slowly in several days/months/years, the nervous mechanism adapts to the altered pressure and looses the sensitivity for the changes. Kidneys regulate arterial blood pressure by two ways: 1. By regulation of ECF volume 2. Through renin angiotensin system (RAS)

81. Regulation of blood pressure by renin - angiotensin

82. HORMONAL MECHANISM FOR REGULATION OF BLOOD PRESSURE

83. LOCAL MECHANISM FOR REGULATION OF BLOOD PRESSURE LOCAL VASOCONSTRICTORS Local vasoconstrictor substances are derived from vascular endothelium. These substances are called endothelium-derived constricting factors (EDCF). Common EDCF are endothelins (ET), which are peptides with 21 amino acids. Three types of endothelins ET1, ET2 and ET3 are identified so far. Endothelins are produced by stretching of blood vessels. These peptides act by activating phospholipase, which in turn activates prostacyclin and thromboxane A2. These two substances cause constriction of blood vessels and increase the blood pressure.

84. MEASURMENT OF CARDIAC FUNCTION Serum cardiac enzymes (CK, LDH, Lipid profile, Blood coagulation tests) Radiographic examination Chest radiography Cardiac fluoroscopy Angiography Cardiac catheterization ECG Echocardiography

85. Cardiovascular Diseases

86. CIRCULATORY SHOCK Shock is a general term that refers to the depression or suppression of body functions produced by any disorder. Circulatory shock refers to the shock developed by inadequate blood flow throughout the body.

87. STAGES OF CIRCULATORY SHOCK Circulatory shock occurs in three stages: 1. First stage or compensated stage 2. Second stage or progressive stage 3. Third stage or irreversible stage

88. First stage or compensated stage

89. Second stage or progressive stage

90. TYPES AND CAUSES OF CIRCULATORY SHOCK Circulatory shock is primarily classified into four types: A. Shock due to decreased blood volume B. Shock due to increased vascular capacity C. Shock due to cardiac disease D. Shock due to obstruction of blood flow

91. TREATMENT FOR CIRCULATORY SHOCK BLOOD TRANSFUSION PLASMA TRANSFUSION ADMINISTRATION OF PLASMA SUBSTITUTES ADMINISTRATION OF SYMPATHOMIMETIC DRUGS ADMINISTRATION OF GLUCOCORTICOIDS OXYGEN THERAPY BY CHANGING THE POSTURE

92. HEART FAILURE

93. TYPES OF HEART FAILURE Systolic Heart Failure 2. Diastolic Heart Failure 3. Right Sided Heart Failure 4. Left Sided Heart Failure